The bms balance wires solder is good for sure
I might need to get a fatter soldering tip for the output wires
Thanks, I’ll try to lower the power next time and see how they look
not all the time, though it can help
you just need to make sure you apply good heat to get the solder flowing
flux is a big help if you burn up the rosin in the solder already (not all solder has rosin core but it’s easy to check)
if you got lead free solder, switch to6040 to 6337 solder instead
i would also recommend more isolation between cells/more structural elements, hot glue won’t always hold even if it’s heatshrunk (ie strapping(?) tape)
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0.2mm nickel plated steel? Is this correct? Pure nickel is the standard for batteries, not plated steel
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Yes, 0.2 nickel plated steel.
Standard ebike batteries draw 15a - 35a. Nothing like the 60a-150a we see in esk8. These strips are fine for low current applications such as ebikes.
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I’m not familiar with plated current ratings, just wanted to point it out to make sure there was no issue
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I am not a fan of the sharp nickel corners over the positive terminals. The balance cables should be run over fishpaper, not on the bare cells. Also if the balance cables cross, there should be fishpaper in between them. Most if not all spot welds are too hot, and I can see that you blew through the nickel a few times. I am a little worried about nickel on nickel connections usually, as they are hard to actually weld on robustly. The solder joints look like they will hold, but they don’t look clean. Probably low quality solder. But for an ebike, these issues are probably all passable, even though not ideal. I’ve seen worse in Chinese production ones from the factory… If you were to build a pack for an esk8 or escooter, then you would have to keep all these extra things in mind. I personally build all my ebike packs to meet the esk8 standards.
However:
You absolutely need fishpaper under the folded nickel here! That’s really important
If you want some inspiration you can check out my thread. There are a couple ebike battery packs in there.
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Thanks for the feedback guys
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I agree with marketthrowaway. This doesn’t look like a good solder joint to me. Looks kinda cold and blobby.
Before you solder stuff together, put a healthy amount of flux on both things. heat and tin both things. Then heat them together and you’ll have a happy solder joint.
Otherwise, it looks like a pretty good pack to me. No other notes besides what people have pointed out.
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Oh yeah lol. You don’t wanna be using that in esk8 at all. That’s why those joints look the way they do.
Too many recommendations I could make, I’ll let somebody else. But any genuine 63/37 or 60/40 will be way better for you.
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Austerity solder? But we huff lead fumes for shinye results
Yup, or MG Chemicals.
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Oh snap! Thanks for the heads up
Is there anything special I need to consider with leaded solder?
(Other than washing my hands after)
I spent way too many years of my younger life soldering in poorly ventilated areas w/nothing pulling fumes out of my face (insert joke here)
Now I pretty much refuse to do a single joint without.
Just any fan placed infront of the iron pulling the fumes away is good enough. You don’t have to have serious ventilation, just getting the initial fumes out of your face. It’s moreso for the rosin than the lead (I think)
If you have small kids or pets in the house, that’s when you’d want to consider real ventilation. Like, I think a bird would actually die quickly.
You can always solder outside if doing low volume tho.
But yeah. Fan.
Cleaning up your joints with a bristle brush & isopropyl is also good practice, but not a requirement.
Buy standalone rosin flux while you’re getting new solder tho. If just a puck of paste, keep the puck around but also mix a bit of the paste w/isopropyl & put it in a syringe with a fine-tip luer lock or something. Very helpful to have around.
A wet sponge & metal scrunchy is also good if you don’t already have them - I haven’t used unleaded in a while, but I think leaded generally makes a bit more mess on your tip to regularly clean off.
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this seems like minimalist cell isolation.
I love this solder. Bought it off @monsterbuilder ’s recommendation a while back and never looked back. Flows great.
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That’s completely fine, no need for more fishpaper there as long as the P groups are held together by hot glue and/or fiberglass tape. I also use this method for similar layouts and I think I saw Glyphiks used it too a while ago.
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